The small number of dust particles in the system and their large kinetic energy make it impossible to use the notion of “temperature” to describe the dynamics of dust particles in gas discharge without substantiation. We simulated the isolated and open systems of dust particles based on the molecular dynamics method and suggested the substantiation of applying the term “temperature” to describe the dynamics of the system of dust particles in the gas discharge plasma. The closeness of the equilibrium velocity distribution for a small number of particles and the Maxwell distribution for isolated and open systems is shown. It is found that the average kinetic energy precisely coincides with the velocity distribution parame ter of the dust particles. The necessity of separation the temperature of the horizontal motion and the temperature of the vertical motion of dust particles is shown.